Method of Handling On-Off State of a Cell and Related Communication Device

ABSTRACT

A method of handling an on-off state of a cell for a communication device comprises receiving a first downlink (DL) control information (DCI) in a first subframe from a network, wherein the first DCI indicates at least one first on-off state of at least one first subframe of a first cell of the network; and determining an on-off state of a second subframe of the first cell according to the first DCI, wherein the at least one first subframe comprises the second subframe.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.61/992,262, filed on May 13, 2014 and incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method used in a wirelesscommunication system and related communication device, and moreparticularly, to a method of handling an on-off state of a cell andrelated communication device.

2. Description of the Prior Art

A long-term evolution (LTE) system supporting the 3rd GenerationPartnership Project (3GPP) Rel-8 standard and/or the 3GPP Rel-9 standardare developed by the 3GPP as a successor of the universal mobiletelecommunication system (UMTS) for further enhancing performance of theUMTS to satisfy increasing needs of users. The LTE system includes a newradio interface and a new radio network architecture that provides highdata rate, low latency, packet optimization, and improved systemcapacity and coverage. In the LTE system, a radio access network knownas an evolved universal terrestrial radio access network (E-UTRAN)includes multiple evolved Node-Bs (eNBs) for communicating with multipleuser equipments (UEs), and for communicating with a core networkincluding a mobility management entity (MME), a serving gateway, etc.,for Non-Access Stratum (NAS) control.

A LTE-advanced (LTE-A) system, as its name implies, is an evolution ofthe LTE system. The LTE-A system targets faster switching between powerstates, improves performance at the coverage edge of an eNB, increasespeak data rate and throughput, and includes advanced techniques, such ascarrier aggregation (CA), coordinated multipoint (CoMP)transmissions/reception, uplink (UL) multiple-input multiple-output(UL-MIMO), licensed-assisted access (LAA) using LTE, etc. For a UE andan eNB to communicate with each other in the LTE-A system, the UE andthe eNB must support standards developed for the LTE-A system, such asthe 3GPP Rel-10 standard or later versions.

The UE may need to monitor control channels of cells of the eNB, whenthe UE communicates with the eNB via the cells, i.e., carrieraggregation (CA) is supported. In certain situations, one or more of thecells may be turned off by the eNB, and the UE does not need to monitorthe cell(s) which is turned off and power consumption of the UE can bereduced. The cell(s) which is turned off may be turned on again or a newcell may be turned on (i.e., added) to improve throughput of the UE.However, tens of milliseconds (e.g., 10-60 ms) are needed for switchingon-off states of the cells via a higher layer signaling (i.e., networkcoordination time and/or media access control (MAC) delay). A transitiontime (i.e., delay) needed for switching the on-off states of the cellsis great, and operations of the UE and the eNB are not efficient.Accordingly, throughput of the UE is degraded.

Thus, how to improve efficiency of the switching of the on-off state ofthe cell is an important problem to be solved.

SUMMARY OF THE INVENTION

The present invention therefore provides a method and relatedcommunication device for handling an on-off state of a cell to solve theabovementioned problem.

A method of handling an on-off state of a cell for a communicationdevice comprises receiving a first downlink (DL) control information(DCI) in a first subframe from a network, wherein the first DCIindicates at least one first on-off state of at least one first subframeof a first cell of the network; and determining the on-off state of asecond subframe of the first cell according to the first DCI, whereinthe at least one first subframe comprises the second subframe.

A method of performing a communication operation via a cell for acommunication device comprises receiving a downlink (DL) controlinformation (DCI) in a subframe in a period from a network, wherein theDCI indicates at least one on-off state of at least one subframe in theperiod of a first cell of the network and the at least one on-off stateis specific to the communication device; and performing at least onecommunication operation in the at least one subframe according to the atleast one on-off state.

A method of performing a communication operation via a cell for acommunication device comprises receiving information of a number ofavailable DCIs for a first period from a network; receiving a first DCIin a first subframe in a first period from the network and determiningthat the first subframe of a cell is in an on state specific to thecommunication device; receiving a second DCI in a second subframe in thefirst period after the first subframe from the network and determiningthat the second subframe of the cell is in the on state specific to thecommunication device, if the number of available DCIs is not achieved;and stopping to receive any DCI in the first period and determining thatat least one first subframe of the cell in a rest of the first period isin an off state specific to the communication device, if the number ofavailable DCIs is achieved.

A method of performing a communication operation via a cell for acommunication device comprises receiving a first DCI in a first subframein a first period from a network and determining that the first subframeof a cell is in an on state specific to the communication device;receiving a second DCI in a second subframe in the first period afterthe first subframe from the network and determining that the secondsubframe of the cell is in the on state specific to the communicationdevice, if the first DCI indicates an existence of the second DCI; andstopping to receive any DCI in the first period and determining that atleast one first subframe of the cell in a rest of the first period is inan off state specific to the communication device, if the first DCIindicates that a next DCI does not exist.

These and other objectives of the present invention will no doubt becomeobvious to those of ordinary skill in the art after reading thefollowing detailed description of the preferred embodiment that isillustrated in the various figures and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a wireless communication systemaccording to an example of the present invention.

FIG. 2 is a schematic diagram of a communication device according to anexample of the present invention.

FIG. 3 is a flowchart of a process according to an example of thepresent invention.

FIG. 4 is a schematic diagram of DCIs for an on-off state of a subframeaccording to an example of the present invention.

FIG. 5 is a schematic diagram of DCIs for an on-off state of a subframeaccording to an example of the present invention.

FIG. 6 is a schematic diagram of DCIs for an on-off state of a subframeaccording to an example of the present invention.

FIG. 7 is a flowchart of a process according to an example of thepresent invention.

FIG. 8 is a schematic diagram of a DCI for on-off states of subframesaccording to an example of the present invention.

FIG. 9 is a schematic diagram of DCIs for on-off states of subframesaccording to an example of the present invention.

FIG. 10 is a flowchart of a process according to an example of thepresent invention.

FIG. 11 is a schematic diagram of DCIs for on-off states of subframesaccording to an example of the present invention.

FIG. 12 is a flowchart of a process according to an example of thepresent invention.

FIG. 13 is a schematic diagram of DCIs for on-off states of subframesaccording to an example of the present invention.

DETAILED DESCRIPTION

Please refer to FIG. 1, which is a schematic diagram of a wirelesscommunication system 10 according to an example of the presentinvention. The wireless communication system 10 is briefly composed of anetwork and a plurality of communication devices. The wirelesscommunication system 10 may support a time-division duplexing (TDD)mode, a frequency-division duplexing (FDD) mode, a TDD-FDD jointoperation mode or a licensed-assisted access (LAA) mode. That is, thenetwork and a communication device may communicate with each other viaFDD carrier(s), TDD carrier(s), licensed carrier(s) and/or unlicensedcarrier(s). In addition, the wireless communication system 10 maysupport a carrier aggregation (CA). That is, the network and acommunication device may communicate with each other via multiple cells(e.g., multiple carriers) including a primary cell (e.g., primarycomponent carrier) and one or more secondary cells (e.g., secondarycomponent carriers). The abovementioned cells may be operated in thesame or different duplexing modes. For example, each cell may be a FDDcell (or TDD cell), when the cells are operated in the same duplexingmode. There are also several scenarios, when the cells are operated indifferent duplexing modes (e.g. TDD-FDD joint operation). For example,the primary cell may be operated on a TDD carrier, while a secondarycell may be operated on a FDD carrier. In another example, the primarycell may be operated on the FDD carrier, while the secondary cell may beoperated on the TDD carrier. In another example, the primary cell may beoperated on a licensed carrier, while the secondary cell may be operatedon an unlicensed carrier. For the CA conforming to the 3rd GenerationPartnership Project (3GPP) long-term evolution (LTE) Rel-10/11/12, 5cells (e.g., serving cells) may be supported by the communication deviceand the network. For the CA conforming to the 3GPP LTE Rel-13, 32 cells(e.g., serving cells) may be supported by the communication device andthe network.

In FIG. 1, the network and the communication devices are simply utilizedfor illustrating the structure of the wireless communication system 10.Practically, the network may be a universal terrestrial radio accessnetwork (UTRAN) comprising at least one Node-B (NB) in a universalmobile telecommunications system (UMTS). In another example, the networkmay be an evolved UTRAN (E-UTRAN) including at least one evolved NB(eNB) and/or at least one relay in a long term evolution (LTE) system, aLTE-Advanced (LTE-A) system or an evolution of the LTE-A system.

Furthermore, the network may also include both the UTRAN/E-UTRAN and acore network, wherein the core network may include network entities suchas Mobility Management Entity (MME), Serving Gateway (S-GW), Packet DataNetwork (PDN) Gateway (P-GW), Self-Organizing Networks (SON) serverand/or Radio Network Controller (RNC), etc. In other words, after thenetwork receives information transmitted by a communication device, theinformation may be processed only by the UTRAN/E-UTRAN and decisionscorresponding to the information are made at the UTRAN/E-UTRAN.Alternatively, the UTRAN/E-UTRAN may forward the information to the corenetwork, and the decisions corresponding to the information are made atthe core network after the core network processes the information. Inaddition, the information may be processed by both the UTRAN/E-UTRAN andthe core network, and the decisions are made after coordination and/orcooperation are performed by the UTRAN/E-UTRAN and the core network.

A communication device may be a user equipment (UE), a low cost device(e.g., machine type communication (MTC) device), a device-to-device(D2D) device, a mobile phone, a laptop, a tablet computer, an electronicbook, a portable computer system, or combination thereof. In addition,the network and the communication device can be seen as a transmitter ora receiver according to direction (i.e., transmission direction), e.g.,for an uplink (UL), the communication device is the transmitter and thenetwork is the receiver, and for a downlink (DL), the network is thetransmitter and the communication device is the receiver.

FIG. 2 is a schematic diagram of a communication device 20 according toan example of the present invention. The communication device 20 may bea communication device or the network shown in FIG. 1, but is notlimited herein. The communication device 20 may include a processingmeans 200 such as a microprocessor or Application Specific IntegratedCircuit (ASIC), a storage unit 210 and a communication interfacing unit220. The storage unit 210 may be any data storage device that may storea program code 214, accessed and executed by the processing means 200.Examples of the storage unit 210 include but are not limited to asubscriber identity module (SIM), read-only memory (ROM), flash memory,random-access memory (RAM), Compact Disc Read-Only Memory (CD-ROM),digital versatile disc-ROM (DVD-ROM), Blu-ray Disc-ROM (BD-ROM),magnetic tape, hard disk, optical data storage device, non-volatilestorage unit, non-transitory computer-readable medium (e.g., tangiblemedia), etc. The communication interfacing unit 220 is preferably atransceiver and is used to transmit and receive signals (e.g., data,messages and/or packets) according to processing results of theprocessing means 200.

FIG. 3 is a flowchart of a process 30 according to an example of thepresent invention. The process 30 may be utilized in a communicationdevice shown in FIG. 1, to handling an on-off state of a cell of thenetwork. The process 30 may be compiled into the program code 214 andincludes the following steps:

Step 300: Start.

Step 302: Receive a first DL control information (DCI) in a firstsubframe from the network, wherein the first DCI indicates at least onefirst on-off state of at least one first subframe of a first cell of thenetwork.

Step 304: Determine the on-off state of a second subframe of the firstcell according to the first DCI, wherein the at least one first subframecomprises the second subframe.

Step 306: End.

According to the process 30, the communication device receives a firstDCI in a first subframe from the network, wherein the first DCIindicates at least one first on-off state of at least one first subframeof a first cell of the network. Then, the communication devicedetermines the on-off state of a second subframe of the first cellaccording to the first DCI, wherein the at least one first subframe mayinclude the second subframe. That is, the at least one first on-offstate indicated by the DCI may be used for determining the on-off stateof the second subframe, if the second subframe is included in the atleast one first subframe. An on-off state of a cell can be indicated toa communication device timely according to the process 30, because DCIis transmitted frequently with a short period via a physical layer.Thus, the on-off state of the cell can be switched with a shorttransition time and low overhead. As a result, throughput of thecommunication device can be improved according to the efficientswitching of the on-off state of the cell.

Realization of the process 30 is not limited to the above description.

According to the process 30, the communication device may furtherreceive a second DCI in a third subframe after the first subframe fromthe network, wherein the second DCI indicates at least one second on-offstate of at least one second subframe of the first cell. Then, thecommunication device may determine the on-off state of the secondsubframe of the first cell according to the first DCI and the secondDCI, wherein the at least one second subframe may include the secondsubframe. That is, the on-off state of the second subframe is determinedaccording to both the first DCI and the second DCI, and the accuracy ofthe determination of the on-off state is thus improved. In one example,the method can be further extended to the case of multiple DCIs, wheremore DCIs are used for determining an on-off state of a subframe. Inthis situation, a decision rule (e.g., majority rule) may be used forprocessing the DCIs. For example, the on-off state may be determinedaccording to the DCIs and the majority rule. The majority rule makes adecision based on which choice dominates. For example, the communicationdevice chooses that the network intends to transmit a bit “1”, if thenumber of received bits “1” is greater than the number of received bits“0”.

FIG. 4 is a schematic diagram of DCIs for an on-off state of a subframeaccording to an example of the present invention. In FIG. 4, an on-offstate of the subframe 4 is to be determined by the communication device.In detail, the communication device receives a first DCI in the subframe0, and the first DCI indicates on-off states of the subframes 1-4 (theat least one first subframe in the process 30) which are “on”, “on”,“on”, “off”, respectively. As shown in FIG. 4, bits of “1110” in thefirst DCI are used for indicating the on-off states of the subframes1-4. Similarly, the communication device receives a second DCI in thesubframe 1, and the second DCI indicates on-off states of the subframes2-5 (the at least one second subframe stated previously) which are “on”,“on”, “off”, “on”, respectively. Bits of “1101” in the second DCI areused for indicating the on-off states of the subframes 2-5. Thecommunication device receives a third DCI in the subframe 2, and thethird DCI indicates on-off states of the subframes 3-6 which are “on”,“off”, “on”, “off”, respectively. Bits of “1010” in the third DCI areused for indicating the on-off states of the subframes 3-6. Thecommunication device receives a fourth DCI in the subframe 3, and thefourth DCI indicates on-off states of the subframes 4-7 which are “off”,“on”, “off”, “off”, respectively. Bits of “0100” in the fourth DCI areused for indicating the on-off states of the subframes 4-7.

Thus, the communication device may determine that the on-off state ofthe subframe 4 (the second subframe in the process 30) is “off”, becauseall of the DCIs indicate that the on-off state of the subframe 4 is“off”. In certain situations, a DCI may not be received correctly, e.g.,due to stability of a wireless link. For example, the third DCI in FIG.4 may indicate that the on-off state of the subframe 4 is “on” due to anerroneous reception, e.g., bits of “1110” in the third DCI may bereceived in the subframe 2. However, the communication device may stilldetermines that the on-off state of the subframe 4 is “off” correctlyaccording to the majority rule, if the other 3 DCIs indicate that theon-off state is “off”.

In one example, the on-off state of the second subframe of the firstcell in the process 30 maybe determined according to the second DCI, ifa consistent on-off state is not obtained according to the first DCI,the second DCI and the majority rule are different. That is, the latestDCI(s) may be used for determining the on-off state, if the majorityrule cannot be performed properly.

FIG. 5 is a schematic diagram of DCIs for an on-off state of a subframeaccording to an example of the present invention. In FIG. 5, an on-offstate of the subframe 4 is to be determined by the communication device.Detail of FIG. 5 can be referred to the description of FIG. 4, and isnot narrated herein. The communication device receives 4 DCIs in thesubframes 0-3. As shown in FIG. 5, bits received in the DCIs are “1111”,“1111”, “1010” and “0100”, respectively. That is, an on-off state of thesubframe 4 is indicated by the fourth bit in the bits “1111”, the thirdbit in the bits “1111”, the second bit in the bits “1010” and the firstbit in the bits “0100”. In other words, the bits “1”, “1”, “0” and “0”in the DCIs are used to indicate the on-off state of the subframe 4. Themajority rule cannot be performed properly, because the number of thebit “1” and the number of the bit “0” are the same. In this situation,the communication device may determine the on-off state of the subframe4 according to the DCIs received in the nearest subframes (e.g., thesubframes 2-3). Thus, the communication device may determine that theon-off state of the subframe 4 is “off”, because the latest two DCIsindicate that the on-off state of the subframe 4 is “off”.

In one example, in the process 30, the communication device may performa blind decoding on a DL control channel of the second subframe of thefirst cell, if the on-off state of the second subframe of the first cellis not indicated by any DCI in a previous subframe. Then, thecommunication device may determine the on-off state of the secondsubframe of the first cell according to a decoding result of the blinddecoding. That is, the communication device may not be able to receiveany DCI indicating the on-off state of the second subframe. Thecommunication device may perform the blind decoding to obtain the on-offstate. The DL control channel may include a physical DL control channel(PDCCH) and/or an enhanced PDCCH (ePDCCH), and is not limited herein.

In one example, the at least one first subframe in the process 30 may beafter the first subframe. That is, on-off state(s) of the subframe(s)maybe indicated by using one or more previous subframes. In one example,the first DCI may be received in the first subframe of the first cell.That is, the on-off state of the first cell may be indicated by thefirst DCI from the same cell, i.e., the first cell may beself-scheduled. In one example, the first DCI may be received in thefirst subframe of a second cell. That is, the on-off state of the firstcell may be indicated by the first DCI transmitted via a different cell,i.e., the first cell may be cross-carrier scheduled. Taking FIG. 4 as anexample, the DCIs may be transmitted via the second cell, while theon-off states of the subframes of the first cell are indicated. Thefirst cell may be a secondary cell, and the second cell may be a primarycell. In one example, the first cell may be a primary cell, and thesecond cell may be a secondary cell. In one example, the first cell andthe second cell may both be primary cells. In one example, the firstcell and the second cell may both be secondary cells. In addition, thefirst cell may be operated in a licensed band, and the second cell maybe operated in an unlicensed band. In one example, the first cell may beoperated in an unlicensed band, and the second cell may be operated in alicensed band. In one example, the first cell and the second cell mayboth be operated in a licensed band. In one example, the first cell andthe second cell may both be operated in an unlicensed band.

FIG. 6 is a schematic diagram of DCIs for an on-off state of a subframeaccording to an example of the present invention. The left-hand side ofFIG. 6 is an example of cross-scheduling. The communication devicereceives a DCI in the subframe 0 of a primary cell (i.e., schedulingcell), and the DCI indicates on-off states of the subframes 1-4 of asecondary cell (i.e., scheduled cell). The right-hand side of FIG. 6 isan example of self-scheduling. The communication device receives a DCIin the subframe 0 of a cell, and the first DCI indicates on-off statesof the subframes 1-4 of the same cell.

In one example, the first DCI in the process 30 may be configured with anewly defined DCI format. That is, the format of the first DCI is notlimited to a legacy format defined in the 3GPP standard. In anotherexample, the at least one first on-off state of the at least one firstsubframe of the first cell may be indicated by a new field of the firstDCI. That is, the first DCI maybe configured with a legacy DCI formatwith the new field.

In one example, the at least one first on-off state in the process 30may be indicated by a plurality of bits for the at least one firston-off state and a time delay for indicating a distance between thefirst subframe and an initial subframe of the at least one firstsubframe. Taking the first row of FIG. 4 as an example, the bits are“1110” for the first DCI, and the time delay is 1. For the second row ofFIG. 4, the bits are “1101” for the first DCI, and the time delay is 1.Note that the bits and the time delay are simply an example forrepresenting the subframes and the on-off states of the subframes. Otherrepresentations may also be used for realizing the present invention,and is not limited herein.

In one example, the second subframe in the process 30 is in a pluralityof subframes which is predetermined or is configured by the network. Theplurality of subframes may be all subframes in a frame. That is, thecommunication device may need to receive (e.g., detect) a DCI in each ofthe subframes. In another example, the communication device may need toreceive (e.g., detect) a DCI in each of a subset of all the subframes.

FIG. 7 is a flowchart of a process 70 according to an example of thepresent invention. The process 70 may be utilized in a communicationdevice shown in FIG. 1, to handling an on-off state of a cell of thenetwork. The process 70 may be compiled into the program code 214 andincludes the following steps:

Step 700: Start.

Step 702: Receive a DCI in a subframe in a period from the network,wherein the DCI indicates at least one on-off state of at least onesubframe in the period of a first cell of the network and the at leastone on-off state is specific to the communication device.

Step 704: Perform at least one communication operation in the at leastone subframe according to the at least one on-off state of the network.

Step 706: End.

According to the process 70, the communication device receives a DCI ina subframe in a period from the network, wherein the DCI may indicate atleast one on-off state of at least one subframe in the period of a firstcell of the network and the at least one on-off state is specific to thecommunication device. Then, the communication device performs at leastone communication operation in the at least one subframe according tothe at least one on-off state of the network. That is, the at least oneon-off state may not be real on-off state(s) of the first cell, but isspecific for the communication device to perform the at least onecommunication operation in the at least one subframe. For example, anon-off state of a subframe of the first cell maybe anon state (or an offstate) specific for the communication device, when the first cell isactually in the on state. In another example, the on-off state of thesubframe of the first cell may be the off state specific for thecommunication device, when the first cell is actually in the off state.

In other words, the communication device only needs to perform a DCIdetection (e.g., blind decoding) for receiving the DCI in the subframe,and stops to perform at least one DCI detection for at least one DCI inthe at least one subframe. Thus, the at least one-off state can be seenas data scheduling for the at least one subframe. An on state of asubframe means that the subframe is scheduled for a communicationoperation, and an off state of a subframe means that the subframe is notscheduled for a communication operation. As a result, power consumptionof the communication device is reduced because unnecessary DCIdetections are avoided.

Furthermore, an on-off state of a cell can be indicated to acommunication device timely according to the process 70, because DCI istransmitted frequently with a short period via a physical layer. Thus,the on-off state of the cell can be switched with a short transitiontime and low overhead. As a result, throughput of the communicationdevice can be improved according to the efficient switching of theon-off state of the cell.

Realization of the process 70 is not limited to the above description.

In one example, the communication device may determine that the at leastone on-off state of the at least one subframe is an off state, if theDCI is not received in the subframe. That is, the communication devicedetermines that all subframes in the period are in the off state, if theDCI in the subframe is not detected. In one example, the communicationdevice may receive the DCI by performing DCI detection (e.g., blinddecoding) in the subframe.

In one example, a communication of the at least one communicationoperation may include a transmission or a reception. That is, the atleast one communication operation may include transmission(s),reception(s), or combination of transmission(s) and reception(s). In oneexample, the at least one subframe in the process 70 may be after thesubframe. That is, on-off state(s) of the subframe(s) may be indicatedby using a previous subframe. In one example, the DCI may be received inthe subframe of the first cell. That is, the at least one on-off stateof the first cell may be indicated by the DCI from the same cell, i.e.,the first cell may be self-scheduled. In one example, the DCI may bereceived in the subframe of a second cell. That is, the at least oneon-off state of the first cell may be indicated by the DCI transmittedvia a different cell, i.e., the first cell may be cross-carrierscheduled. The first cell may be a secondary cell, and the second cellmay be a primary cell. In one example, the first cell may be a primarycell, and the second cell may be a secondary cell. In one example, thefirst cell and the second cell may both be primary cells. In oneexample, the first cell and the second cell may both be secondary cells.In addition, the first cell may be operated in a licensed band, and thesecond cell may be operated in an unlicensed band. In one example, thefirst cell may be operated in an unlicensed band, and the second cellmay be operated in a licensed band. In one example, the first cell andthe second cell may both be operated in a licensed band. In one example,the first cell and the second cell may both be operated in an unlicensedband.

In one example, the DCI in the process 70 may be configured with a newlydefined DCI format. That is, the format of the DCI is not limited to alegacy format defined in the 3GPP standard. In another example, the atleast one on-off state of the at least one subframe of the first cellmay be indicated by a new field of the DCI. That is, the DCI may beconfigured with a legacy DCI format with the new field.

FIG. 8 is a schematic diagram of a DCI for on-off states of subframesaccording to an example of the present invention. In FIG. 8, 3 bits in aDCI are used for indicating the on-off states of subframes 0-4, and each3 bits indicate an on-off state of a corresponding subframe. Forexample, the communication device may determine that the on-off state ofthe subframe 2 is an on state, if the bits “010” are included in theDCI. According to the present invention, the communication deviceperforms a DCI detection in the subframe 0, and does not need to performDCI detections in the subframes 1-4. In addition, the communicationdevice determines the subframes 1-4 are in an off state, if the DCI isnot received in the subframe 0. Thus, cross-subframe scheduling can berealized according to the present invention, while power consumption isreduced by avoiding unnecessary DCI detections.

In one example, the period in the process 70 may be a predeterminedvalue or may be dynamically configured by the network. The period may bea frame (e.g., consist of 10 subframes) or half of the frame (e.g.,consist of 5 subframes), and is not limited.

FIG. 9 is a schematic diagram of DCIs for on-off states of subframesaccording to an example of the present invention. In FIG. 9, the periodis 5 subframes, and the on-off states of 5 subframes are indicatedperiodically according to the period. The DCI in the subframe 0 mayindicate on-off states of the subframes 1-4 and the DCI in the subframe5 may indicate on-off states of the subframes 6-9. When combining withthe example in FIG. 8, 3 bits in the DCI can be used for indicating anon-off state of a corresponding subframe. According to the presentinvention, the communication device performs DCI detections in thesubframes 0 and 5, and does not need to perform DCI detections in thesubframes 1-4 and 6-9. Thus, cross-subframe scheduled can be realizedaccording to the present invention, while power consumption is reducedby avoiding unnecessary DCI detections.

FIG. 10 is a flowchart of a process 100 according to an example of thepresent invention. The process 100 may be utilized in a communicationdevice shown in FIG. 1, to handling an on-off state of a cell of thenetwork. The process 100 may be compiled into the program code 214 andincludes the following steps:

Step 1000: Start.

Step 1002: Receive information of a number of available DCIs for a firstperiod from the network.

Step 1004: Receive a first DCI in a first subframe in a first periodfrom the network and determining that the first subframe of a cell is inan on state specific to the communication device.

Step 1006: Receive a second DCI in a second subframe in the first periodafter the first subframe from the network and determining that thesecond subframe of the cell is in the on state specific to thecommunication device, if the number of available DCIs is not achieved.

Step 1008: Stop to receive any DCI in the first period and determiningthat at least one first subframe of the cell in a rest of the firstperiod is in an off state specific to the communication device, if thenumber of available DCIs is achieved.

Step 1010: End.

According to the process 100, the communication device receives (e.g.,detects) information of a number of available DCIs for a first periodfrom the network. The communication device may receive a first DCI (ifavailable) in a first subframe in a first period from the network, andmay determine that the first subframe of a cell is in an on statespecific to the communication device. Then, the communication device mayreceive a second DCI in a second subframe in the first period after thefirst subframe from the network and determining that the second subframeof the cell is in the on state specific to the communication device, ifthe number of available DCIs is not achieved. The communication devicemay stop to receive any DCI in the first period and determining that atleast one first subframe of the cell in a rest of the first period is inan off state specific to the communication device, if the number ofavailable DCIs is achieved. In other words, the communication devicereceives one or more DCIs in the first period according to the number ofavailable DCIs for the first period. The communication device continuesto receive (e.g., detect) the DCIs in the first period, if the number ofreceived DCIs is smaller than the number of available DCIs. Thecommunication device stops to receive the DCIs in the first period, ifthe number of received DCIs achieves the number of available DCIs .Further, the rest of the subframe(s) in the first period which are notprocessed are determined to be in the off state.

An on-off state of a cell can be indicated to a communication devicetimely according to the process 100, because DCI is transmittedfrequently with a short period via a physical layer. The on-off state ofthe cell can also be determined by the communication device efficiently.Thus, the on-off state of the cell can be switched with a shorttransition time and low overhead. As a result, throughput of thecommunication device can be improved, and power consumption of thecommunication device can be reduced.

Realization of the process 100 is not limited to the above description.

In one example, the communication device may determine that on-offstates of all subframes are an off state, if the information of thenumber of available DCIs is not received in the first subframe. That is,the communication device determines that all subframes in the firstperiod are in the off state, if the number of available DCIs for thefirst period is not received.

In one example, the first subframe and the second subframe may beconsecutive subframes. That is, the DCIs are received sequentially inthe subframes without skipping a certain subframe. In addition, thecommunication device may determine at least one second subframe withinthe first subframe and a third subframe in the first period is in the onstate specific to the communication device, when the number of availableDCIs is achieved in the third subframe. That is, all subframe(s) withinthe first subframe (where the first DCI is detected) and the lastsubframe (where the last DCI is detected), including the first subframeand the last subframe, are determined to be in the on state specific tothe communication device.

In one example, the communication device may receive a third DCI in afourth subframe in a second period from the network, and may determinethat the fourth subframe of the cell is in the on state specific to thecommunication device. That is, the communication device may repeat theprocess 100 to receive DCIs in one or more periods, to obtain on-offstates of subframes of a cell in the periods, wherein the on-off statesare specific to the communication device. Detail of the operation of thecommunication device for each of the periods can be referred to theprevious description, and is not narrated herein.

In one example, the cell in the process 100 may be a primary cell, orthe cell may be a secondary cell. The cell may be operated in a licensedband, or may be operated in an unlicensed band.

FIG. 11 is a schematic diagram of DCIs for on-off states of subframesaccording to an example of the present invention. Real on-off statesoperated by a cell are shown at the top, and on-off states operated by(i.e., specific to) a communication device are shown at the bottom. Aperiod for receiving DCIs is a frame (i.e., 10 subframes), and thecommunication device receives information of the number of availableDCIs which is 3 for the period. Starting from the subframe 0, thecommunication device tries to detect a DCI in each of the subframessequentially until 3 DCIs are received, and determines that thesubframes that have been gone through are in the on state. In thepresent example, the communication device receives DCIs DCI1-DCI3 in thesubframes 0, 2 and 3, respectively. The communication device stops todetect any DCI after the DCI DCI3 in the subframe 3 is obtained, becauseall the available DCIs are received. Accordingly, the communicationdevice determines that the subframes 0-3 are in the on state, andsubframes (i.e., the subframes 4-9) after the subframe 3 are in an offstate. In addition, the communication device determines the subframes1-9 are in the off state, if information of the number of available DCIsis not received in the subframe 0. Thus, the communication device mayperform communication operations in the subframes 0-3, and reduces powerconsumption (e.g., turns off) in the subframes 4-9.

FIG. 12 is a flowchart of a process 120 according to an example of thepresent invention. The process 120 may be utilized in a communicationdevice shown in FIG. 1, to handling an on-off state of a cell of thenetwork. The process 120 may be compiled into the program code 214 andincludes the following steps:

Step 1200: Start.

Step 1202: Receive a first DCI in a first subframe in a first periodfrom a network and determining that the first subframe of a cell is inan on state specific to the communication device.

Step 1204: Receive a second DCI in a second subframe in the first periodafter the first subframe from the network and determining that thesecond subframe of the cell is in the on state specific to thecommunication device, if the first DCI indicates an existence of thesecond DCI.

Step 1206: Stop to receive any DCI in the first period and determiningthat at least one first subframe of the cell in a rest of the firstperiod is in an off state specific to the communication device, if thefirst DCI indicates that a next DCI does not exist.

Step 1208: End.

According to the process 120, the communication device may receive afirst DCI in a first subframe in a first period from a network anddetermining that the first subframe of a cell is in an on state specificto the communication device. Then, the communication device may receivea second DCI in a second subframe in the first period after the firstsubframe from the network and determining that the second subframe ofthe cell is in the on state specific to the communication device, if thefirst DCI indicates an existence of the second DCI. The communicationdevice may stop to receive any DCI in the first period and determiningthat at least one first subframe of the cell in a rest of the firstperiod is in an off state specific to the communication device, if thefirst DCI indicates that a next DCI does not exist. In other words, thecommunication device continues to receive (e.g., detect) the DCIs in thefirst period, if a next DCI is indicated available. The communicationdevice stops to receive the DCIs in the first period, if a next DCI isindicated not available. Further, the rest of the subframe(s) in thefirst period which are not processed are determined to be in the offstate.

An on-off state of a cell can be indicated to a communication devicetimely according to the process 120, because DCI is transmittedfrequently with a short period via a physical layer. The on-off state ofthe cell can also be determined by the communication device efficiently.Thus, the on-off state of the cell can be switched with a shorttransition time and low overhead. As a result, throughput of thecommunication device can be improved, and power consumption of thecommunication device can be reduced.

Realization of the process 120 is not limited to the above description.

In one example, the first subframe and the second subframe may beconsecutive subframes. That is, the DCIs are received sequentially inthe subframes without skipping a certain subframe. In addition, thecommunication device may determine at least one second subframe withinthe first subframe and a third subframe in the first period is in the onstate specific to the communication device, when a third DCI in thethird subframe indicates that a next DCI does not exist. That is, allsubframe(s) within the first subframe (where the first DCI is detected)and the last subframe (where the last DCI is detected), including thefirst subframe and the last subframe, are determined to be in the onstate specific to the communication device.

In one example, the communication device may receive a fourth DCI in afourth subframe in a second period from the network, and may determinethat the fourth subframe of the cell is in the on state specific to thecommunication device. That is, the communication device may repeat theprocess 120 to receive DCIs in one or more periods, to obtain on-offstates of subframes of a cell in the periods, wherein the on-off statesare specific to the communication device. Detail of the operation of thecommunication device for each of the periods can be referred to theprevious description, and is not narrated herein.

In one example, the cell in the process 120 may be a primary cell, orthe cell may be a secondary cell. The cell may be operated in a licensedband, or may be operated in an unlicensed band.

FIG. 13 is a schematic diagram of DCIs for on-off states of subframesaccording to an example of the present invention. Real on-off statesoperated by a cell are shown at the top, and on-off states operated by(i.e., specific to) a communication device are shown at the bottom. Aperiod for receiving the DCIs is a frame (i.e., 10 subframes). At thebeginning, the communication device receives a DCI in the subframe 0,and determines that an on-off state of the subframe 0 is “on”, whereinthe DCI (e.g., a bit “1” in the DCI) indicates that a next DCI exists.Accordingly, the communication device tries to detect a DCI in thesubframe 1. The communication device receives a DCI in the subframe 1,and determines that an on-off state of the subframe 1 is “on”, whereinthe DCI (e.g., a bit “1” in the DCI) indicates that a next DCI exists.Similarly, the communication device tries to detect a DCI in thesubframe 2. The communication device receives a DCI in the subframe 2,and determines that an on-off state of the subframe 2 is “on”, whereinthe DCI (e.g., a bit “0” in the DCI) indicates that a next DCI does notexist. The communication device stops to detect any DCI after thesubframe 2. Accordingly, the communication device determines that thesubframes 0-2 are in the on state, and subframes after the subframe 2(i.e., the subframes 3-9) are in the off state. Thus, the communicationdevice may perform communication operations in the subframes 0-2, andreduces power consumption (e.g., turns off) in the subframes 3-9.

Those skilled in the art should readily make combinations, modificationsand/or alterations on the abovementioned description and examples. Theabovementioned description, steps and/or processes including suggestedsteps can be realized by means that could be hardware, software,firmware (known as a combination of a hardware device and computerinstructions and data that reside as read-only software on the hardwaredevice), an electronic system, or combination thereof. An example of themeans maybe the communication device 20.

Examples of the hardware may include analog circuit(s), digitalcircuit(s) and/or mixed circuit(s). For example, the hardware mayinclude ASIC(s), field programmable gate array(s) (FPGA(s)),programmable logic device(s), coupled hardware components or combinationthereof. In another example, the hardware may include general-purposeprocessor(s), microprocessor(s), controller(s), digital signalprocessor(s) (DSP(s)) or combination thereof.

Examples of the software may include set(s) of codes, set(s) ofinstructions and/or set(s) of functions retained (e.g., stored) in astorage unit, e.g., a computer-readable medium. The computer-readablemedium may include SIM, ROM, flash memory, RAM, CD-ROM/DVD-ROM/BD-ROM,magnetic tape, hard disk, optical data storage device, non-volatilestorage unit, or combination thereof. The computer-readable medium(e.g., storage unit) may be coupled to at least one processor internally(e.g., integrated) or externally (e.g., separated). The at least oneprocessor which may include one or more modules may (e.g., be configuredto) execute the software in the computer-readable medium. The set(s) ofcodes, the set(s) of instructions and/or the set(s) of functions maycause the at least one processor, the module(s), the hardware and/or theelectronic system to perform the related steps.

Examples of the electronic system may include a system on chip (SoC),system in package (SiP), a computer on module (CoM), a computer programproduct, an apparatus, a mobile phone, a laptop, a tablet computer, anelectronic book or a portable computer system, and the communicationdevice 20.

To sum up, the present invention provides a method for handling anon-off state of a cell. The on-off state of the cell can be switchedwith a short transition time and low overhead. As a result, according tothe efficient switching of the on-off state of the cell, throughput ofthe communication device can be improved, and power consumption of thecommunication device can be reduced.

Those skilled in the art will readily observe that numerousmodifications and alterations of the device and method may be made whileretaining the teachings of the invention. Accordingly, the abovedisclosure should be construed as limited only by the metes and boundsof the appended claims.

What is claimed is:
 1. A method of handling an on-off state of a cellfor a communication device, the method comprising: receiving a firstdownlink (DL) control information (DCI) in a first subframe from anetwork, wherein the first DCI indicates at least one first on-off stateof at least one first subframe of a first cell of the network; anddetermining an on-off state of a second subframe of the first cellaccording to the first DCI, wherein the at least one first subframecomprises the second subframe.
 2. The method of claim 1, furthercomprising: receiving a second DCI in a third subframe after the firstsubframe from the network, wherein the second DCI indicates at least onesecond on-off state of at least one second subframe of the first cell;and determining the on-off state of the second subframe of the firstcell according to the first DCI and the second DCI, wherein the at leastone second subframe comprises the second subframe.
 3. The method ofclaim 2, wherein the on-off state of the second subframe of the firstcell is determined according to the first DCI, the second DCI and amajority rule.
 4. The method of claim 3, wherein the on-off state of thesecond subframe of the first cell is determined according to the secondDCI, if a consistent on-off state is not obtained according to the firstDCI, the second DCI and the majority rule.
 5. The method of claim 1,further comprising: performing a blind decoding on a DL control channelof the second subframe of the first cell, if the on-off state of thesecond subframe of the first cell is not indicated by any DCI in aprevious subframe; and determining the on-off state of the secondsubframe of the first cell according to a decoding result of the blinddecoding.
 6. The method of claim 1, wherein the at least one firstsubframe is after the first subframe.
 7. The method of claim 1, whereinthe first DCI is received in the first subframe of the first cell, or isreceived in the first subframe of a second cell of the network.
 8. Themethod of claim 7, wherein the first cell is a primary cell or asecondary cell, and the second cell is a primary cell or a secondarycell.
 9. The method of claim 7, wherein one of the first cell and thesecond cell is operated in a licensed band, and the other one of thefirst cell and the second cell is operated in an unlicensed band. 10.The method of claim 1, wherein the first DCI is configured with a newlydefined DCI format.
 11. The method of claim 1, wherein the at least onefirst on-off state of the at least one first subframe of the first cellis indicated by a new field of the first DCI.
 12. The method of claim 1,wherein the second subframe is in a plurality of subframes which ispredetermined or is configured by the network.
 13. The method of claim1, wherein the at least one first on-off state is indicated by aplurality of bits for the at least one first on-off state and a timedelay for indicating a distance between the first subframe and aninitial subframe of the at least one first subframe.
 14. A method ofperforming a communication operation via a cell for a communicationdevice, the method comprising: receiving a downlink (DL) controlinformation (DCI) in a subframe in a period from a network, wherein theDCI indicates at least one on-off state of at least one subframe in theperiod of a first cell of the network and the at least one on-off stateis specific to the communication device; and performing at least onecommunication operation in the at least one subframe according to the atleast one on-off state.
 15. The method of claim 14, further comprising:determining that the at least one on-off state of the at least onesubframe is an off state, if the DCI is not received in the subframe.16. The method of claim 14, wherein the communication device receivesthe DCI by performing a DCI detection in the subframe, and stops toperform at least one DCI detection for at least one DCI in the at leastone subframe.
 17. The method of claim 14, wherein a communication of theat least one communication operation comprises a transmission or areception in a corresponding subframe of the at least one subframe. 18.The method of claim 14, wherein the at least one subframe is after thesubframe.
 19. The method of claim 14, wherein the DCI is received in thesubframe of the first cell, or is received in the subframe of a secondcell of the network.
 20. The method of claim 14, wherein the first cellis a primary cell or a secondary cell, and the second cell is a primarycell or a secondary cell.
 21. The method of claim 14, wherein one of thefirst cell and the second cell is operated in a licensed band, and theother one of the first cell and the second cell is operated in anunlicensed band.
 22. The method of claim 14, wherein the DCI isconfigured with a newly defined DCI format.
 23. The method of claim 14,wherein the at least one on-off state of the at least one subframe ofthe first cell is indicated by a new field of the DCI.
 24. A method ofperforming a communication operation via a cell for a communicationdevice, the method comprising: receiving information of a number ofavailable DCIs for a first period from a network; receiving a first DCIin a first subframe in the first period from the network and determiningthat the first subframe of a cell of the network is in an on statespecific to the communication device; receiving a second DCI in a secondsubframe in the first period after the first subframe from the networkand determining that the second subframe of the cell is in the on statespecific to the communication device, if the number of available DCIs isnot achieved; and stopping to receive any DCI in the first period anddetermining that at least one first subframe of the cell in a rest ofthe first period is in an off state specific to the communicationdevice, if the number of available DCIs is achieved.
 25. The method ofclaim 24, further comprising: determining that on-off states of allsubframes in the first period are the off state, if the information ofthe number of available DCIs is not received in the first subframe. 26.The method of claim 24, wherein the first subframe and the secondsubframe are consecutive subframes.
 27. The method of claim 26, furthercomprising: determining at least one second subframe within the firstsubframe and a third subframe in the first period is in the on statespecific to the communication device, when the number of available DCIsis achieved in the third subframe.
 28. The method of claim 24, furthercomprising: receiving a third DCI in a fourth subframe in a secondperiod from the network and determining that the fourth subframe of thecell is in the on state specific to the communication device.
 29. Themethod of claim 24, wherein the cell is a primary cell or a secondarycell.
 30. A method of performing a communication operation via a cellfor a communication device, the method comprising: receiving a first DCIin a first subframe in a first period from a network and determiningthat the first subframe of a cell is in an on state specific to thecommunication device; receiving a second DCI in a second subframe in thefirst period after the first subframe from the network and determiningthat the second subframe of the cell is in the on state specific to thecommunication device, if the first DCI indicates an existence of thesecond DCI; and stopping to receive any DCI in the first period anddetermining that at least one first subframe of the cell in a rest ofthe first period is in an off state specific to the communicationdevice, if the first DCI indicates that a next DCI does not exist. 31.The method of claim 30, wherein the first subframe and the secondsubframe are consecutive subframes.
 32. The method of claim 31, furthercomprising: determining at least one second subframe within the firstsubframe and a third subframe in the first period is in the on statespecific to the communication device, when a third DCI in the thirdsubframe indicates that a next DCI does not exist.
 33. The method ofclaim 30, further comprising: receiving a fourth DCI in a fourthsubframe in a second period from the network and determining that thefourth subframe of the cell is in the on state specific to thecommunication device.
 34. The method of claim 30, wherein the cell is aprimary cell or a secondary cell.